Can coating varnishes containing manganese soap drier and steam cracked distillate resins



United States Patent CAN COATING VARNISHES CONTAINING MAN- troleum fractions boiling in the range of 20 to 280' C.

, Intermediate fractions boiling within this range, such as the 30-60 C. fraction may also be'iised advantageously. Both of these fractions obviously are free of butadiene GANESE SOAP DRIER AND STEAM CRACKED 5 (which boils at about --4 C.) and other materials boil- DISTILLATE RESINS ing belgw 20 C, John F. McKay cranford NJ" assign to Essa Research In general, heavier petroleum fractions such as naphtha, and En Ineedng Com 8 co oration of Delaware "gas or], and the like, are cracked at relatively low pres- 8 m sures and at temperatures of 1000 to 1500 F. in the pres- N0 D lwlng- Alipliclfloll December 1953 10 ence of steam and for relatively short contact times. The 400,737 gas and liquid streams produced contain large quantities 6 M CL F23. of diolefins and ol efins, particularly 1n the C to C range. 7) The naphtha distillate streams obtained by steam cracking operations contain large amounts of diolefins, olefins, The present invention relates to an improved film for aromatics and some parafiins and naphthenes. A typical use in coating the interior of cans to be used for constream shows diolefins, 5 1% olefins, 27% aromatics, sumable goods, such as food stuffs and the like. and 2% paraflins and naphthenes. It has been the practice to coat the interior surfaces These naphtha distillate streams are treated with 0.25- of cans, to be used as containers for consumable goods, 2.5% of a Friedel-Crafts type catalyst such as aluminum with tin to prevent the corrosion of the sheet steel by the 20 chloride, aluminum bromide, boron trifluoride and the goods contained therein. However, in times of emergency like, or solutions, slurries or complexes thereof. The tin often becomes in short supply and substitutes are in reactions are conducted at temperatures in the range of demand. Up to the present time, however,=,it has not -100 to 100 C. (preferably -35 to 65 0.). Rebeen found possible to substitute all of the tin used in sidual catalyst is quenched by suitable methods such as coating the interior of the can with other coatings because addition of methyl alcohol and subsequent filtration, water of the failure of such coatings. and/or caustic washing and the final solution is then Commercially, flat sheets of can stock are coated with stripped of unreacted hydrocarbons and low molecular varnish and the films must survive subsequent can forming weight oils by vacuum or steam distillation. The product operations. Inferior varnishes are most apt to fail in the is a substantially non-aromatic unsaturated hydrocarbon countersink area of can covers. This sharply bent area resin, since analysis indicates that little of the aromatic is around the circumference where the cover is crimped constituents of the feed enters the composition. .Data to the can body. The can varnishes must have good water on a number of such reactions and reaction products are and chemical resistances, both at room temperature and summarized in the following Table I.

TABLE I Run No 1 a s 4 s a 7 s 9 Approx. Bolling Pt. 0.) M 20-125 38-130 48-130 30-280 85-260 Compo)s ltion, Wt. Percent (Apiiibieflns so 20 10.4 12 15 15 Oleflns 50 4s 50.0 50.9 oz Aromatics- Benzene 25 22 28.5 4.5 Toluene o 7 7.0 10.1 10 Higher 7.2 16 Paratfins, N aphthenes 10 1 1 1 1. 2 15 Polymerization:

Catalyst A101; A101; A101; A101; A101. BF; [A1017 A1011 BF: Temperature C.) i5 25 I00 4 45 25 25 20 Resin, Wt. Pereent 05-85 25-35 10 30-30 18-23 15 20-30 10 11 Soft. Pt. (3) -85 70-00 00 85-9 -95 74 -100 70 i l The exact softening conditions, etc.

at high food-processing temperatures. Curing of the films must be rapid to fit plant operations, i.e., 12 minutes or less. All of these considerations call for a high quality varnish.

All commercial varnishes have undesirably long cook times and high weight loss during preparation.

It has now been found that the above disadvantages can be overcome by the use of certain synthetic hydrocarbon resins in the preparation of varnishes provided a rigid curing schedule is used. The varnishes prepared in accordance with the present'invention have shorter cook times, less volatile losses and better colors than control varnishes made from commercial can coating resins. The resulting cured films are the equal of the commercial films in chemical resistance, metal adhesion, and resistance to fracture during can forming operations.

'The basic resins used in the present invention are prepared by the polymerization of steam cracked pcpoint and yield depends upon the degree of work-up oi the resin, such as stripping Resins particularly suitable for the purpose of this invention may also be prepared by the polymerization of steam crackedpetroleum fractions boiling in the range of 30 to 60 C. and containing piperylene. The following table shows characteristic compositions of these distillate streams:

' Component: Wt. percent Isoprene 15-0 Piperylenes 15-60 C; acyclic and cyclic olefins 70-35 Paraflins and naphthenes 0-3 C,+ 0-2 piperylene is unsatisfactory s resin feed because of excessive amount of gel formed during polymerization.

The reactive components in the above streams are polymerized in the presence of an aluminum halide catalyst under conditions described above.

The yield and softening point of the final resin will depend on the degree of stripping. Stripping to a pot tem perature of 200-300 C. at 1-50 mm. Hg, preferably 240-270 C. at 1 to 5 mm. Hg has given acceptable resin products. Steam stripping at temperatures of 250-270 C. can also be employed to produce high softening point resins.

The resins thus obtained are made into varnishes of preferably 20 gallon oil length (20 gallons of oil per 100 pounds of resin) by cooking with preferably 50-50 mixtures of tung and alkali-refined linseed oils. The oil length of the varnishes may be varied from about 15 gallons to about 25 gallons. Shorter oil length varnishes produce excessively brittle films and longer oil length varnishes give films which have inferior chemical resistance. The ratio of tung oil to linseed oil may be varied from about 75-25 to about 25-75 parts per volume. If more tung oil is used, the varnishes are too unstable in storage. It more linseed oil is used relative cook times of all the varnishes are undesirably longer. Part or all of the tung oil may be replaced by such oils as oiticica, fish, or dehydrated castor and part or all of the linseed oil may be replaced by such oils as perilla or soybean. The cooked varnish is then suited for can coatings when applied in thin films of .35 mil or less.

Films of this low thickness are especially adapted for coating metal cans and closures because they can be rapidly applied, cured and fabricated from flat coated metal sheets into container parts. The end use requires rigid resistance to corrosion, steam processing and certain chemicals in order to protect the metal and the product contained in the can.

The base metal to which these coatings may be applied are either can makers quality steel or stock coated with tin of insufiicient thickness to give adequate protection during processing.

In using the above varnishes as can coating films, it is vital to control the curing in order to obtain adequate protection. This is accomplished, in accordance with the present invention, by the addition to the varnish of .003% to .02%, preferably about 0.005 to 0.015% by weight of a manganese soap drier. The soap may be naphthenate, linoleate, octoate, resinate, abietate, oleate, benzoate, benzoyl benzoate, crotonate, butyrate or the like. The film is then cured at 215 C. to 245 C., for 8-20 minutes, preferably 10 to 16 minutes. When tin plated stock is used, curing temperatures should not exceed 232 C., the melting point of tin. With can makers quality steel, curing temperatures up to 245' C. may be used although at the longer cure times the films may become excessively brittle. When 8 minute cures are used, grease and caustic resistance of the films may be poor at the lower baking temperatures. Longer cure times (16 minutes) give films with satisfactory resistance but are less desirable because of production schedules of existing commercial can-coating machines. The temperature of cure for varnish films is normally not over 245' C., since if higher temperatures are used the resulting films are brittle and easily lose adhesion. However, the above temperature is necessary for the varnishes of the present invention since otherwise inferior coatings are obtained.

The advantages of the present invention will be apparcat from the following examples:

A fraction of a steam cracked distillate boiling in the range of about 36 to 48 C. and containing about 38 volume percent of piperylene and 14 volume percent of isoprene was polymerized with 1.0% by weight of aluminum chloride at a temperature of 20' C. The reaction products were quenched with a 5% sulfuric acid solution, water washed thoroughly and then stripped to a bottoms temperature of 270 C. at 5 mm. Hg to recover the resin in 64.6% yield having a softening point of 89 C. and a color of 0. This resin is designated Piperylene Resin 1. Another resin was made by the same technique from the same feed with 40% n-hexane diluent added. Affistripping, 64.0% yield of resin was obtained which had a softening point of 86 C. and a color of 0. This resin is designated Piperylene Resin 2." Another fraction of a steam cracked distillate boiling in the range of about 36 to 48 C. and containing 39% piperylene .and 6% isoprene was polymerized with 1% by weight,

of aluminum chloride dissolved in ethyl chloride at a temperature of 20 C. (:9). After washing and stripping as above, 72% yield of resin was obtained which had a softening point of 84 C. and a color of 0. This resin is designated Piperylene Resin 3." A wide-cut fraction of a steam cracked distillate boiling in the range of about to 130 C. which, according to analysis, consisted approximately of 14% dienes, 43% olefins and 43% aromatics and saturated hydrocarbons was polymerized with 1% aluminum chloride at 20 C. (15). After stripping, 32% yield of resin was obtained whic had a softening point of 99 C. and a color of 2. This resin is designated Resin from wide cut feed.

Twenty gallon oil length varnishes were made from the above resins by cooking them with a -50 mixture of tung and alkali-refined linseed oil. A similar varnish was made from a commercial can-coating resin. The data are shown in Table I].

TABLE II Preparation of can coating varnishes from experimental resins as w. a a...

B Bl Resin Cement, of Var min. percent Color 9 2'14" 0. Loss NVM 60% arsol NVM uent) Piperylene Resin 1 6. 2 3. 3 9 Piperylene Resin 2.--. 4.0 2.0 B Piperylane Resin 3.-.. b0 1. 6 1. 3 7 Resin from Wide Out Feed--. 90 4. a 1. e 14 Commercial can-coating resln.. 11.0 as is linseed oil. Reduced with Varso The above data show that the cook time and weight percent loss of the varnishes made from the non-aromatic unsaturated hydrocarbon resins are less than those for the commercial can-coating varnish. The colors of the varnishes from the piperylene resins are also less than that of the commercial varnish.

EXAMPLE 2 To each of the varnishes prepared in Example 1 was added .0075 manganese drier. The varnishes were then spread in very thin films (0.14 to 0.28 mil) on test panels and cured by baking. The films were then tested for failure at the countersink area of the can-covers by bending the test panels through over a 141 inch mandrel followed by immersing in boiling water for fifteen minutes. The number of film fractures on a given area of the bend was then observed through a 50 power microscope after contacting the surface with copper sulfate solution. Chemical resistance of the films was also determined. The following data shown in Table III were obtained.

TABLE IIE Evaluation of can-coating varnishes o it? with t on R b c 7 percen em. as. onntersink Area Adhesion Mn at- Q Panel No. Resin Component or Varnish 111 :2155. l d

' F1 in Swar Film Min. C. B 4 G 4 Ci 4 0 Thiek- 'Hard- Fallnesa, ness ures mils 1 Plperylene, Resin 1 12 204 0.30 5 5 0 0 0.23 32 0 12 215 0.20 o o o a 0.26 as o a 16 21a 0. 2e 0 o o 6 a 12 227 0. 26 0 0 0 8 0.27 20 0 i5 227 0. 27 0 0 0 2 0 Piperylene, Resin 2 12 204 0. 20 0 5 0 0 0.19 32 0 7 12 227 0. 2o 0 0 0 8 0.20 31 0 0 Plperyleue, Resin 3 12 204 0.19 0 4 0 8 0.19 42 14 0 12 227 0.14 0 0 0 0 0.14 88 4 12 204 0.26 0 7 0 6 0. 25 28 0 10 Resin from Wide-Cut Feed.... 8 227 0. 20 0 7 0 4 0. 20

12 244 0. 20 0 0 0 0 0.20 42 B 12 Commercial Can-Coating 12 215 0.20 0 0 0 0 0.23 29 0 Resin (Control).

I 20 gallon oil length varnishes mode with 50/50 mixture of tung and alkali-refined linseed oils Code.- 0 unaiiected, 1-7

degrees oi softening and discoloration, 8-9

' Mea ure oi adhesion and flexibility at countersink area of can covers. 4 8-soap (2 hr.); G-grease (2 hr. OiNa0H (1 hr., 1%); 0;Na0H(1/2 hr. 150 F., 0.25%).

The above data show that the varnishes prepared according to the present invention give films with as good resistance as the control when cured at 215-245 C. for at least 8 minutes.

To recapitulate, the present invention provides broadly a new can coating varnish which is obtained by cooking together a mixture of 25-75 parts by volume of a vegetable oil chosen from the groupconsisting of tung oil, oiticica oil, fish oil with 75-25 parts by volume of another vegetable oil chosen from the group consisting of linseed oil, perilla oil and soybean oil and an olefin-diolefin resin from a steam-cracked petroleum fraction boiling between about 20 C. and 280 C. which contains about 15-60% piperylene; the ratio being about 100 lbs. of resin per 15-25 gallons of the total vegetable oil mixture. A manganese soap drier is added to the varnish in an amount ranging from .003 to .02 wt. percent based on the varnish. The mixture is applied in a thin film on a suitable base and cured at a temperature of 215245 C. for 8 to minutes.

The nature of the present invention having been thus fully set forth and specific examples of the same given, what is claimed as new and useful and desired to be secured by Letters Patent is:

1. A coating composition which when applied to a metallic surface and cured at about 2l5-245 C. for about 8 to 20 minutes forms a protective coating for said surface which has improved resistance to cracking and chemicals; said composition .comprising a mixture of about to 75 parts by volume of a vegetable oil selected from the group consisting of tung oil, oiticica oil, fish oil, and dehydrated castor oil, and about 75 to 25 parts by volume of another vegetable oil selected from the group consisting of linseed oil, perilla oil and soybean oil, about 0.003% to about 0.02% by weight based on the total composition of a manganese carboxylate soap drier and an olefin-diolefin resin obtained by polymerizing a steamcrackedpetroleum fraction boiling between about 20 C. to 280 C. which contains about 15 to 60% piperylene; the ratio between the resin and the vegetable oil mixture being about 100 lbs. resin per 15-25 gallons of the vegetable oil mixture said manganese carboxylate soap drier being the sole metallic carboxylate soap drier employed.

2. A coating composition in accordance with claim 1 in which the manganese carboxylate soap drier is selected from the group consisting of manganese naphthenate, linoleate, octoate, resinate, abietate, oleate, benzoate,

fllm stripped ironi test panel. Low values are desirable.

benzoyl benzoate, crotonate, butyrate, and combinations thereof, and is present in an amount of about 0.005% to about 0.01% by weight.

3. A coating composition according to claim 1 in which the resin is prepared by polymerizing the steam-cracked petroleum fraction boiling between 30130 C. in the presence of catalytic amounts of a Friedel-Crafts catalyst at a temperature between about C. and +100 C.

4. An article comprising a metallic structure having thereon a coating comprising a layer of a composition which has been cured for about 8 to 20 minutes at about 215 to 245 C.; said composition comprising a vegetable oil mixture consisting essentially of about 25 to 75 parts by volume of a vegetable oil selected from the group consisting of tung oil, oiticica oil, fish oil, and dehydrated castor oil, and about 75 to 25 parts by volume of another vegetable oil selected from the group consisting of linseed oil, perilla oil, and soybean oil, about 0.003% to about 0.02% by wt. based on the total composition of a manganese carboxylate soap drier, and an olefin-diolefin resin from a steam-cracked hydrocarbon fraction boiling between about 20 to 280? C. which contains about 15 to 60% piperylene and about 30 to 70% olefins; the ratio of the resin to the vegetable oil mixture being about 100 lbs. of resin per 15 to 25 gallons of said vegetable oil mixture said manganese carboxylate soap drier being the sole metallic carboxylate soap drier employed.

5. The article of claim 4 in which the manganese carboxylate soap drier is selected from the group consisting of manganese naphthenate, linoleate, octoate, resinate, abietate, oleate, benzoate, benzoyl benzoate, crotonate, butyrate, and mixtures thereof, and is present in an amount of from about 0.005 .to 0.015% by weight, and the curing time is between about 10 and 16 minutes.

6. The article of claim 4 inwhich the steam-cracked petroleum fraction boils between about 30 C. and 60 C., about 0.25% to 2.5% of the Friedel-Crafts catalyst is employed, and the polymerization temperature is between about 35 C. and +65 C.

References Cited in the file of this patent Hamner July 3, 1956 

1. A COATING COMPOSITION WHICH WHEN APPLIED TO A METALLIC SURFACE AND CURED AT ABOUT 215-245*C. FOR ABOUT 8 TO 20 MINUTES FORMS A PROTECTIVE COATING FOR SAID SURFACE WHICH HAS IMPROVED RESISTANCE TO CRACKING AND CHEMICALS; SAID COMPOSITION COMPRISING A MIXTURE OF ABOUT 25 TO 75 PARTS BY VOLUME OF A VEGETABLE OIL SELECTED FROM THE GROUP CONSISTING OF TUNG OIL, OITICICA OIL, FISH OIL, AND DEHYDRATED CASTOR OIL, AND ABOUT 75 TO 25 PARTS BY VOLUME OF ANOTHER VEGETABLE OIL SELECTED FROM THE GROUP CONSISTING OF LINSEED OIL, PERILLA OIL AND SOYBEAN OIL, ABOUT 0.003% TO ABOUT 0.02% BY WEIGHT BASED ON THE TOTAL COMPOSITION OF A MANGANESE CARBOXYLATE SOAP DRIER AND AN OLEFIN-DIOLEFIN RESIN OBTAINED BY POLYMERIZING A STEAMCRACKED PETROLEUM FRACTION BOILING BETWEEN ABOUT 20*C. TO 280*C. WHICH CONTAINS ABOUT 15 TO 60% PIPERYLENE; THE RATIO BETWEEN THE RESIN AND THE VEGETABLE OIL MIXTURE BEING ABOUT 100 LBS. RESIN PER 15-25 GALLONS OF THE VEGETABLE OIL MIXTURE SAID MANGANESE CARBOXYLATE SOAP DRIER BEING THE SOLE METALLIC CARBOXYLATE SOAP DRIER EMPLOYED. 